Excavating equipment is commonly used for construction projects that require builders and contractors to move large amounts of earth, rocks and other materials. Backhoes and other types of excavating equipment commonly include a boom, or dipper stick, that extends from the main body, and a bucket pivotally attached to the end of the arm. The bucket is typically controlled by hydraulics mounted above the arm. While these types of excavators are well suited for moving loose dirt and small rocks, they are not well suited for picking up larger objects that do not fit easily into the bucket.
Some excavators also include a fixed or movable thumb that opposes the movement of the bucket and facilitates grabbing and moving rocks, pipes, concrete, trees, and other larger objects. The use of thumbs can decrease the amount of time required for a given project. Examples of excavating equipment with a fixed or movable thumb may be found in U.S. Pat. Nos. 4,131,210; 4,375,345; 4,466,494; 4,519,739; 4,770,597; 4,803,788; 4,804,309; 4,845,867; 4,932,832; 5,111,602; 5,553,408; 5,678,332; 5,813,822; 5,972,933; 6,209,237; 6,260,294; 6,385,870; 6,640,471; Japanese Patent No. 4-202917; and PCT Application WO 89/12145, the entire disclosures of which are herein incorporated by reference for all purposes.